The thousands of pinholes you get from putting drywall mud on painted surfaces is definitely a drag. A reaction of some sort. Often I’m doing painting anyway so prime spackel and prime again. Another method I found works is. Do the first coat as per usual as it seems not not happen on the first coat. Second coat. Lay on heavy. Let sit a minute or so. Wipe it ALL off let sit briefly and coat as usual. A pain but seems to work. It’s definitely a timing thing as to how long to let it sit. The longer between steps the better.